Advances in Bacterial Cellulose Production: A Scoping Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Manuscript ID: coatings-3237475

Title: Advances in Bacterial Cellulose Production: Scoping Review

I find this review to be only a superficial treatment of the subject matter, and thus cannot recommend its publication. Examples of issues I find problematic are as follows:

 The authors have attempted to tie the production of bacterial cellulose (BC) with the sustainable development goals (SDGs), without explaining how the two are connected. For instance, SDG 12 is mentioned (responsible production and consumption). It is not clear how BC production will promote responsible consumption.

 It is stated “government, businesses and organizations” need to collaborate and promote the use of bacterial cellulose. What organizations, and why the government? No explanation is provided.

 In section 3, entitled “*Potential* applications of bacterial cellulose”, but the language used by authors appears to suggest that there *currently are products available in the market* made up of or containing BC. I know there is no utilization of BC for textile fiber production on a commercial scale at present, and am fairly certain BC is not found in products for human consumption and use (e.g., in food products, cosmetics, implants etc.) due to concerns over microbial residues in the material. If there are indeed commercial products, the authors should cite the instances with references.

 Further down in the manuscript, there are multiple repetitions of the same message, only phrased differently. For example:

“Static cultures can produce bacterial cellulose, where bacteria are incubated in a liquid culture medium without movement or agitation”

“Static culture is a production method for manufacturing bacterial cellulose and other microbial products”

“Bacterial cellulose is obtained through fermentation in an aqueous medium in a liquid environment containing specific nutrients”

 Specific technologies are mentioned as being advantageous, but without explanation of why. For example:

“Bioreactors allow for more precise control of culture conditions and can improve productivity [4]; however, the quality of bacterial cellulose is reduced as biofilm crystallinity decreases [34].” – What conditions are more precisely controlled and why is greater precision required? Why is the crystallinity reduced, and does it happen with all bioreactors?

 “Using rotating discs in the bioreactor helps maintain a larger contact surface between the bacteria and the culture medium, improving the productivity and quality of the cellulose produced [27]. Moreover, this culture system allows modification of culture conditions that differ from conventional culture methods, such as disk rotation speed, disk diameter, disk thickness and distance between disks [39].” – Why are disc diameters, rotation speed and distance between discs important?

 “According to the study presented in [26], the spherical bubble column bioreactor features a unique geometry that improves oxygen transfer and mitigates problems of limited oxygen supply during bacterial cellulose production” – What is unique, how does it improve oxygen transfer, and what are the problems with limited oxygen supply?

 “An innovative technology for producing bacterial cellulose involves using an airlift reactor modified with wire mesh tubes (Figure 5c) [26]. This alternative involves using a bioreactor that improves oxygen transfer and addresses problems of limited oxygen supply during bacterial cellulose production. This technology allows the use of active bacterial strains [10], genetic modification [31], the use of different carbon sources and culture media [27], and the optimization of conditions in bioreactors.” – What is an airlift, and is it especially suited for active bacterial strains, genetically modified organisms, different carbon sources and culture media? If yes, why? What limitations do other technologies have that does not allow the use of for example, active bacterial strains?

 “An optofluidic device [48] has been developed that uses a convolutional neural network to analyze bacterial cellulose dispersion patterns, allowing high-throughput profiling of cellulose production and morphology for a single bacterium.” Why is it important to analyze BC dispersion patterns and morphology? Can the morphology of a single bacterium really be determined with the device?

 The paper has many more of such statements, which appear simply to be repeated from the references cited, but without any explanations of their importance or relevance.

Author Response

Response to Reviewer 1  

1. Summary

"Dear Reviewer, we appreciate the time you have taken to review our manuscript. We have addressed all your observations, which have helped improve the clarity and enrich the document. Additionally, we have included updated information regarding the use of bacterial cellulose as evidenced in scientific literature. Furthermore, we have enriched the document with the comments from the other reviewers. We kindly ask that you review our revised manuscript, and we appreciate any further feedback to enhance this review article." 

Let us know if you'd like any other adjustments! 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The first three chapters (the bibliographic study and its methodology, potential applications of BC) seemed promising, but the following part regarding the technologies is totally devoid of a systematic arrangement of the data, with many overlaps and repetitions, a flurry of reviews and punctual experimental articles, with imprecise citations, a very difficult text to follow.

I limit myself to only a few examples:

lines 244-252 mix the bioreactors with the producing strains, their genetic modification, and the composition of the culture media;

lines 245, 262, and 507 refer to wire mesh (tubes) [26], [20,22,24], citations without any relation to the content.

[10] is present in line 248 referring to active strains, but its place is only in line 369, referring to agro-industrial wastes as carbon sources;

[26] presents the author named R.R. et al, instead of Reshmy R. and the other authors;

[33] has nothing to look for in line 592, it refers to the agitator's configuration for production improvement.

You should make a major revision, grouping each subject separately: strains, their genetic improvement, culture media, fermentation technologies, and equipment, downstream processing, with the necessary attention to citations, mentioning separately the reviews and experimental papers, the latest having to be a majority.

The figures are almost okay, only small editing corrections are necessary (e.g. immobilized bioreactor instead of "immovilized" reactor).

 

The conclusions could be improved by systematizing and emphasizing actions to overcome the limitation of economic competitiveness, including the selection of appropriate applications.  

 

Author Response

Summary 

"Dear Reviewer, we appreciate the time you have taken to review our manuscript. We have addressed all your observations, which have helped improve the clarity and enrich the document. Additionally, we have included updated information regarding the use of bacterial cellulose as evidenced in scientific literature. Furthermore, we have enriched the document with the comments from the other reviewers. We kindly ask that you review our revised manuscript, and we appreciate any further feedback to enhance this review article." 

Let us know if you'd like any other adjustments!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The review is written compactly, systematically and useful for the reader.

To increase the quality, I recommend:

1.     Include quantitative data on the properties and applications of BCs, e.g. as indicated in: https://doi.org/10.1016/j.carbpol.2023.120915.

2.     In the article, practically no attention is paid to patents. It would be appropriate to provide at least some data from recent work. And supplement with newer data (after 2020).

3.     In the context of a wider BC particle size distribution, what are the most suitable techniques to obtain BC with a narrower particle size distribution?

4.    The article should be supplemented with a more detailed (quantitative, or semiquantitative) evaluation of the economic aspects of the preparation or production of BC, and applications. I recommend an inspiration by the article. https://doi.org/10.1016/j.jobab.2024.05.003.

Author Response

"Dear Reviewer, we appreciate the time you have taken to review our manuscript. We have addressed all your observations, which have helped improve the clarity and enrich the document. Additionally, we have included updated information regarding the use of bacterial cellulose as evidenced in scientific literature. Furthermore, we have enriched the document with the comments from the other reviewers. We kindly ask that you review our revised manuscript, and we appreciate any further feedback to enhance this review article."

Let us know if you'd like any other adjustments!

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Many thanks for revising the manuscript.

Author Response

Thank you very much for taking the time to review this manuscript. We appreciate the time spent and all the comments that served to enhance the manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors The presentation looks much better now.  Some corrections and clarifications are still necessary: Lines 49 and 210     B.C. instead of C.B. Lines 291-292 You cited [30] an airlift reactor modified with wire mesh tubes. [30] is a review referring to [79] hao Y.-p.; Sugano Y.; Kouda T.; Yoshinaga F.; Shoda M.  Production of bacterial cellulose by Acetobacter xylinum with an air-lift reactor. Biotechnol. Tech. 1997,11,11, 829–832, where the airlift reactor contains no wire mesh. Please cite this specific paper and correct the presentation accordingly (without wire mesh). I understand that the citations highlighted in yellow are the right ones, replacing the previous ones. But in line 337, you kept the previous incorrect ones in yellow and introduced [25,45] instead of [25,44], as you wrote in the cover letter response. Please make the correct modification. Line 402 Introduce "contains" ("table 2 contains"). Please check again all of the citations. 

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding corrections highlighted in red in the re-submitted files. We appreciate the time spent and all the comments that served to enhance the manuscript

Author Response File: Author Response.pdf